The biomechanical properties of the cornea were studied by bidirectional applanation in a control group of healthy individuals and in patients with normotensive and primary open-angle glaucoma. The studies were performed before and after use of antihypertensive drugs. Static perimetric findings were used to evaluate the stabilization of a glaucomatous process. Elevated intraocular pressure was found to be attended by a lower corneal hysteresis-corneal resistance factor ratio. Lowered intraocular pressure resulted in increases in corneal hysteresis and the ratio up to the normal values, which was accompanied by visual field stabilization. An investigation of the biomechanical properties of the cornea and keratopachymetrium should be included into a complex of examination and monitoring of patients with normotensive and primary open-angle glaucoma since hypodiagnosis of elevated intraocular pressure may be due to the possible effect of corneal properties on tonometric parameters.